AbstractLaminated veneer bamboo (LVB) is a relatively new building product made from layers of glued bamboo and used in applications similar to lumber. Few studies exist on its mechanical performan...
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AbstractCross-laminated timber (CLT) is a massive panel product made from orthogonal layers of solid-sawn lumber. Because of its composite nature and engineered layup, CLT provides the possibility ...
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Plastered straw bales are composite building materials used as load bearing walls in sustainable structures worldwide. Structural testing of the composite is necessary to establish mechanical properties for practitioner use and for... more
Plastered straw bales are composite building materials used as load bearing walls in sustainable structures worldwide. Structural testing of the composite is necessary to establish mechanical properties for practitioner use and for building code acceptance. This study investigates the compressive behavior of individual two-string rye straw bales when plastered using the most commonly used plasters in temperate climate zones, specifically: lime, lime-cement, and clay. A total of forty-eight specimens were tested to failure under compressive loading in two orientations: on-edge and flat. It was found that results vary not only according to plaster type but also according to bale orientation: on edge bales tended to fail due to buckling of the plastered skins while flat oriented bales failed primarily due to plaster crushing. Importantly, all cases exceeded the maximum load capacity proposed for the 2015 International Residential Code with the lowest factor of safety being 1.8 for on-e...
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ABSTRACT
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ABSTRACT This paper presents a study in which a universal-type test machine was configured to apply torsion load-to-failure to estimate the orthotropic shear strengths of full-size laminated veneer lumber (LVL). The objective of the study... more
ABSTRACT This paper presents a study in which a universal-type test machine was configured to apply torsion load-to-failure to estimate the orthotropic shear strengths of full-size laminated veneer lumber (LVL). The objective of the study is to provide insight and detail to a lesser known torsion test setup, while at the same time estimating the torsional shear strength of 1.9E eastern species LVL, hitherto unknown. It was found that at large angles of twist of approximately 23° or more, the test apparatus experienced slippage at the bearings and had the potential to become unstable due to high lateral forces. This was not an obstacle for calculating the shear strength of LVL in this study, as it is a relatively noncompliant material, but likely would be an issue for more compliant materials. The mean in-plane and through-thickness plane shear strengths of 1.9E eastern species LVL were estimated to be in the range of 7.2-11.2 MPa and 5.9-7.3 MPa, respectively.
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This study examines the differences between two environmental assessment methods for the K-12 education sector: the United States Green Building Council's (USGBC) LEED Schools Version 3.0 and the British Research Establishment's... more
This study examines the differences between two environmental assessment methods for the K-12 education sector: the United States Green Building Council's (USGBC) LEED Schools Version 3.0 and the British Research Establishment's (BRE) BREEAM Education issue 2.0. Credit requirements are compared side-by-side and against recommendations from researchers in areas such as acoustics, lighting and indoor environment quality. Strengths in the two schemes and areas for improvement are highlighted, with acknowledgement that each scheme offers components and techniques from which the other could benefit.
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Recent work in USA and Germany has indicated that continuous glued-in metal plates provide a highly rigid and ductile shear connection between wood and concrete in composite action. It is the degree of stiffness found in the following... more
Recent work in USA and Germany has indicated that continuous glued-in metal plates provide a highly rigid and ductile shear connection between wood and concrete in composite action. It is the degree of stiffness found in the following system that allows the suggesfull use of ...
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Wood composites offer great promise in the materials sector of wind energy engineering. The project presented herein is part of an on-going effort to address the benefits, drawbacks, and overall feasibility of implementing wood composite... more
Wood composites offer great promise in the materials sector of wind energy engineering. The project presented herein is part of an on-going effort to address the benefits, drawbacks, and overall feasibility of implementing wood composite materials as structural components of utility-scale wind turbine blades. This computational experiment observes the loading on all of the structural components of a 5-megawatt wind turbine as the blade mass is reduced by up to 30% of a baseline case. It is shown that these reductions in blade mass, which could be achieved by substituting some components of the fiberglass blade with wood composites, reduce forces in the rest of the turbine and support structure.
The University of Massachusetts, Amherst recently constructed the John W. Olver Design Building, a fourstory, 87,600 ft2 (8,100 m2) structure which is today still one of the first institutional buildings in the US to employ engineered... more
The University of Massachusetts, Amherst recently constructed the John W. Olver Design Building, a fourstory, 87,600 ft2 (8,100 m2) structure which is today still one of the first institutional buildings in the US to employ engineered mass timber. It is also a showcase example for wood-concrete composite systems, off-site construction principles, and has become a teaching tool for explaining this type of construction to professionals and their next generation students at UMass which are being educated right within this structure. This case-study article examines three specific components of this building that all espouse off-site construction principles often in combination with on-site additions: the hybrid glulam-steel “zipper” truss, the cross-laminated timber (CLT) shear cores, and the CLT-concrete composite panel system. These comprise the core of the structural system and offer many lessons for similar buildings. Introduction In early 2017, the University of Massachusetts Amhe...
Shade trees provide many benefits but can cause damage if they fail. Despite the potential for costly litigation that sometimes arises when damage occurs, there are no investigations of bending moments and stresses involved in failure of... more
Shade trees provide many benefits but can cause damage if they fail. Despite the potential for costly litigation that sometimes arises when damage occurs, there are no investigations of bending moments and stresses involved in failure of shade trees. Twenty-four shade trees of three species in the genus Acer were pulled to failure at a suburban property in Massachusetts, U.S. The maximum load and distance to failure were used to calculate maximum bending moment; stress at the point of failure was calculated from bending moment and stem cross-sectional dimensions. No trees uprooted, and failures were categorized as either stem at a lateral branch(es) or the attachment of codominant stems. Failures of codominant stems required one-half of the stress of stem failures. Similarly, failures of codominant stems occurred at only 45% of wood strength, whereas stem failures occurred at 79% of wood strength. Prediction of maximum bending moment from tree morphometric data was more reliable tha...
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A nonlinear model has been formulated to predict the compressive stress-strain behaviour of strand-based wood composites based on the constitutive properties of the wood strands. Prediction models of this type are indispensable for the... more
A nonlinear model has been formulated to predict the compressive stress-strain behaviour of strand-based wood composites based on the constitutive properties of the wood strands. Prediction models of this type are indispensable for the advancement of wood composite materials, not only for the development of new products but also for specific application design. Ultimately, they can be used to gauge the effect of varying raw material characteristics with limited fabrication and testing of the full scale product, resulting in tremendous savings in cost and time. The model requires, as input, an experimental database of the two-dimensional orthotropic, constitutive properties of 2.5 x 19 mm Douglas-fir strands, as well as small laminated wood composites. A materially nonlinear finite element code with extended capacity to perform Monte Carlo simulations has been developed. The nonlinear constitutive behaviour of the wood strands is characterized within the framework of rate-independent...
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The purpose of this study was to experimentally and numerically explore the effect of drilled holes in high shear zones of Laminated Veneer Lumber (LVL) beams. A total of 15 full-size shear beam tests were performed on nominal 2x10 1.9E... more
The purpose of this study was to experimentally and numerically explore the effect of drilled holes in high shear zones of Laminated Veneer Lumber (LVL) beams. A total of 15 full-size shear beam tests were performed on nominal 2x10 1.9E Eastern Species LVL specimens with a span of 1829mm. Three different hole diameters were investigated: 44mm, 70mm, and 92mm drilled at quarter span and mid-depth of the beams. A finite element analysis, coupled with the Tsai-Wu strength theory, was carried out on the same beam configurations to investigate the stress distribution around the holes. It was clear from the stress contour maps that the holes disturb the flow of normal and shear stresses in such a way as to develop significant tensile stresses perpendicular to the grain at specific locations around the hole periphery. The transverse tensile stresses lead to relatively consistent failure loads for the LVL due to the lack of cross plies.
The authors investigated the typology and characteristics of recent technology innovation in particleboard and composite materials. Conducting a cluster analysis of data derived from a content analysis of the International... more
The authors investigated the typology and characteristics of recent technology innovation in particleboard and composite materials. Conducting a cluster analysis of data derived from a content analysis of the International Particleboard/Composite Materials Symposium Proceedings, they identified four major clusters of like-type technology innovations – manufacturing, high technology, materials processing, and new products. Equipment makers dominated innovation in all four clusters, and “improved product quality” was the predominant source of economic benefits. Innovations in the manufacturing cluster are characterized as process innovations originated by an equipment maker. Equipment makers provided specific technology, but participation by manufacturers was not unusual. There was no participation by endusers. After “improved product quality,” “reduced energy consumption” was most often cited as a source of economic benefits. High technology innovations are characterized as process i...
Plastered straw bales are composite building materials used as load bearing walls in sustainable structures worldwide. Structural testing of the composite is necessary to establish mechanical properties for practitioner use and for... more
Plastered straw bales are composite building materials used as load bearing walls in sustainable structures worldwide. Structural testing of the composite is necessary to establish mechanical properties for practitioner use and for building code acceptance. This study investigates the compressive behavior of individual two-string rye straw bales when plastered using the most commonly used plasters in temperate climate zones, specifically: lime, lime-cement, and clay. A total of forty-eight specimens were tested to failure under compressive loading in two orientations: on-edge and flat. It was found that results vary not only according to plaster type but also according to bale orientation: on edge bales tended to fail due to buckling of the plastered skins while flat oriented bales failed primarily due to plaster crushing. Importantly, all cases exceeded the maximum load capacity proposed for the 2015 International Residential Code with the lowest factor of safety being 1.8 for on-e...
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This paper discusses the historical and current day need for education in the area of building materials and wood technology as it relates to the economy of Massachusetts. A case study of the Building Materials and Wood Technology... more
This paper discusses the historical and current day need for education in the area of building materials and wood technology as it relates to the economy of Massachusetts. A case study of the Building Materials and Wood Technology (BMATWT) Program at the University of Massachusetts, Amherst is provided. The history of the program and economic and other forces affecting curriculum change are presented. Readers interested in expanding the educational and training offerings for forest products and related industries should benefit from the material presented. A customer-focused approach to curriculum development focusing on students as customers and members of the business community as clients is described. The development of an industry advisory board, student recruitment initiatives, industry relations and interdisciplinary teaching and research are outlined. A core understanding of wood science, building technology, business, and emerging technologies such as engineered wood product...
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Straw bale construction offers a renewable, sustainable and proven alternative to mainstream building methods; still, little is known about its airflow characteristics. To this end, the intent of this paper is to evaluate airtightness of... more
Straw bale construction offers a renewable, sustainable and proven alternative to mainstream building methods; still, little is known about its airflow characteristics. To this end, the intent of this paper is to evaluate airtightness of fully constructed and plastered straw bale walls as well as individual plain straw bales. The first experiment entailed measuring the influence of straw bale orientation on airflow characteristics with the finding that straw bale considered alone has poor air flow-retarding characteristics and that plaster is the primary air barrier. A second experiment involved thirty plastered straw bale specimens using three different plaster types. From this experiment, a crack grading system was developed and is herein proposed as a tool to evaluate plaster performance as an air barrier. A third experiment validated the crack grade system through application on four fully constructed straw bale walls. Practical use of the crack grading system was demonstrated o...
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The aim of this study is to compare brick and straw bale wall systems from environmental, economic and energy perspectives. The choice of basic building materials is an important part of each project and is usually based on professional... more
The aim of this study is to compare brick and straw bale wall systems from environmental, economic and energy perspectives. The choice of basic building materials is an important part of each project and is usually based on professional judgment, taking into consideration the importance of various criteria such as economic, environmental, functional, aesthetic and health aspects. Brick is the most commonly used building material worldwide; whereas straw, though widely available and having many advantageous properties, is still poorly exploited. In this study, wall compositions of both materials were examined assuming passive building standards. Three values -Global Warming Potential (GWP), Primary Energy Input (PEI) and Acidification Potential (AP) -of environmental impact were calculated. It was shown that, considering environmental, economic and energy values, the use of straw bales is a good alternative to brick.
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This paper elucidates the need to consider the effect of volume on brittle material strengths when these strengths are used in a strength theory. Specifically, Weibull weakest-link theory has been implemented with the Tsai-Wu strength... more
This paper elucidates the need to consider the effect of volume on brittle material strengths when these strengths are used in a strength theory. Specifically, Weibull weakest-link theory has been implemented with the Tsai-Wu strength theory to predict the ultimate load carrying capacity of a center point off-axis bending member made from Douglas-fir laminated veneer. Weibull theory has been used
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The current work expands on a three-dimensional, non-linear, stochastic finite-element model previously developed by the author. The model predicts a materially non-linear stress-strain curve for tension, compression and bending... more
The current work expands on a three-dimensional, non-linear, stochastic finite-element model previously developed by the author. The model predicts a materially non-linear stress-strain curve for tension, compression and bending scenarios. It is based on the non-linear constitutive properties of the individual strands, which are characterized within the framework of orthotropic elasto-plasticity. The constitutive model employs the Tsai-Wu yield criterion and an associated flow rule. Failure is marked by an upper bound surface whereupon either perfect plasticity or an abrupt loss of strength and stiffness ensues. The finite element code has also extended the capacity to perform Monte Carlo simulations. The model was further developed to predict the mechanical behavior of parallel-strand lumber (PSL) made from Douglas fir. The physical features of PSL were measured and incorporated into the finite element model and the mechanical behavior of PSL was simulated. Statistical distribution...
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A dimensional stochastic finite element technique is presented herein for simulating the nonlinear behaviour of strand-based wood composites with strands of varying grain-angle. The approach is based on the constitutive properties of the... more
A dimensional stochastic finite element technique is presented herein for simulating the nonlinear behaviour of strand-based wood composites with strands of varying grain-angle. The approach is based on the constitutive properties of the individual strands to study the effects of varying strand characteristics (such as species or geometry) on the performance of the member. The constitutive properties of the strands are found empirically and are subsequently used in a dimensional finite element program. The program is formulated in a probabilistic manner using random variable material properties as input. The constitutive model incorporates classic plasticity theory whereby anisotropic hardening and eventual failure of the material is established by the Tsai–Wu criterion with an associated flow rule. Failure is marked by an upper bound surface whereupon either perfect plasticity (i.e. ductile behavior) or an abrupt loss of strength and stiffness (i.e. brittle behavior) ensues. The ability of this technique to reproduce experimental findings for the stress–strain curves of angle-ply laminates in tension, compression as well as 3 point bending is validated.
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Interest in the engineering performance of bamboo is on the rise primarily due to its rapid regenerative qualities and high strength-to-weight ratio. It has been a standard, sustainable building material for thousands of years in Asia and... more
Interest in the engineering performance of bamboo is on the rise primarily due to its rapid regenerative qualities and high strength-to-weight ratio. It has been a standard, sustainable building material for thousands of years in Asia and South America, where it grows naturally. Although there are many examples of magnificent bamboo structures, standards and documentation on safe and reliable bamboo design are scarce, particularly for connection design. Traditional connections involve friction-tight lashings (eg. ropes and cords of dried grasses) and pin-and-socket connections such as dowels and pegs, but more recent advances have involved integration with steel hardware and concrete. This paper presents bamboo as a feasible alternative building material and presents a review of past, current and emerging technologies to join hollow bamboo culms in structural applications. The paper's intent is to give an overview of the current state of bamboo connection technology and to promo...
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This paper discusses the historical and current day need for education in the area of building materials and wood technology as it relates to the economy of Massachusetts. A case study of the Building Materials and Wood Technology... more
This paper discusses the historical and current day need for education in the area of building materials and wood technology as it relates to the economy of Massachusetts. A case study of the Building Materials and Wood Technology (BMATWT) Program at the University of Massachusetts, Amherst is provided. The history of the program and economic and other forces affecting curriculum